The present invention relates methods and apparatus for making absorbent articles or garments, and more particularly to improved methods and apparatus for making a stretchable absorbent undergarment intended to be worn for absorbing and retaining liquids and waste material.
Currently, there are numerous kinds of wearable garments intended for use as, for example, infant diapers and adult incontinence garments. Some of these garments are reusable, while others are disposable. Regardless of the disposability of the garment, the garment is generally intended to provide several key features such as good absorbency, containment of liquids and waste materials, dry and wet integrity, dry and wet flexibility, surface dryness, low flowback properties, comfort, fit and discreteness.
Probably the single most important feature to the wearer is containment. One approach to achieving superior containment is to focus on improving the absorbent characteristics of the garment. Development of transfer layer structures and the incorporation of superabsorbent materials are two such examples. Even with these advances, containment continues to be the primary issue to the consumer. Looking beyond these absorbency characteristics, another approach is to define the manner with which the undergarment interacts with a body, and to identify the deficiencies of the conventional absorbent products. Several key areas impacting containment are discussed below.
To the degree the undergarment conforms and responds to the body and changing body geometries as movement occurs, its fit is affected. Naturally, containment will improve with a greater or more intimate fit between the undergarment and the body. Several methods, such as folding, elasticizing and molding, have been used in the preshaping of a predominantly planar garment to form a contoured three-dimensional garment for better fit. However, difficulties with each method exist. For example, folding results in a design or configuration which is subject to areas of gapping and fluid channeling along the fold lines. Elasticizing leg areas forms an improved snugging fit, which is generally only effective at the leg openings. Although a molded product appears to offer improved performance, it is currently limited to providing protection for the female body.
Another area influencing containment is pad deformation. The degree to which a garment can maintain its prewear and/or prewet shape directly impacts on its capacity to absorb and contain fluid. For example, it is known that wood pulp-based absorbents tend to become redistributed during body movement, thereby decreasing absorbency in the areas of maximum wetting.
Many current absorbent products or garments are layered materials that are peripherally bonded, but allow shifting between layers. However, rapid absorption or transfer of fluid through multiple layers is enhanced by close contact between those layers. Thus, these absorbent products or garments that are only peripherally bonded create gapping or separation between layers that reduces the fluid transfer and absorbent rates, thereby degrading the containment characteristic of the product.
One of the recurring problems with current absorbent garments is that they sacrifice one or more of the earlier-mentioned key features in order to possess or increase the effect of others. For example, absorbency generally can be maximized with a combination of fluff and superabsorbent, but one of the problems with this combination is its integrity. When dry, fluff tends to be redistributed by movement or activities of the wearer, thereby decreasing its absorbency in the areas of maximum wetting. Similarly, after wetting, the combination tends to gather or cluster into separate masses of wetted fluff, which is very uncomfortable and visibly embarrassing to the wearer.
One solution to the above problem is to provide a mechanism that maintains the integrity of the absorbent material, such as by introducing amounts of binders, synthetic fibers or the like. Though this may increase dry and wet integrity, it generally causes a decrease in flexibility, which to the wearer translates into a relatively stiff-feeling mat or structure.